Bi-Directional Sea Water Circulation Pump for OMC and Volvo Penta GM V6/V8 Engines – Replaces 3853850, 21124846
Bi-Directional Sea Water Circulation Pump for OMC and Volvo Penta GM V6/V8 Engines – Replaces 3853850, 21124846 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Bi-Directional Sea Water Circulation Pump for OMC and Volvo Penta G...
Bi-Directional Sea Water Circulation Pump for OMC and Volvo Penta GM V6/V8 Engines – Replaces 3853850, 21124846 is backordered and will ship as soon as it is back in stock.
Product Details
This is a replacement bi-directional sea water circulation pump for selected OMC Cobra sterndrive/outdrive and Volvo Penta stern-drive applications using GM V6 and small-block V8 marine engines. The engine-mounted pump circulates raw water through the marine cooling system and can operate with either standard or reverse engine rotation.
The company application records identify this as a single pump assembly, not a kit. The records cover OMC engines from 1968–1998 and Volvo Penta GM V6/V8 small-block applications from 1973 and later. Related catalog references also associate this pump style with selected MerCruiser V6 and V8 small-block applications, including 4.3L, 5.0L, and 5.7L engines using the applicable pump configuration.
- Bi-directional design for standard- and reverse-rotation installations.
- Engine-mounted circulation pump for raw-water cooling systems.
- Suitable for GM V6 and small-block V8 marine applications within the stated fitment ranges.
- Sold as one pump assembly. No separate gasket set or installation hardware is listed in the company package record.
Part Number Matrix
Use the references below to compare the pump with the number on your existing component and your engine service information. Part-number references do not replace confirmation of the complete engine application.
| Brand or source | Reference number | Reference type |
|---|---|---|
| OMC | 3853850 | OEM reference |
| OMC | 985429 | OEM reference |
| OMC | 980477 | OEM reference |
| OMC | 382218 | OEM reference |
| OMC | 383953 | OEM reference listed by the company |
| Volvo Penta | 21124846 | OEM reference |
| Volvo Penta | 3853850 | OEM reference |
| Volvo Penta | 856364 | OEM reference |
| Volvo Penta | 835390 | OEM reference |
| Sierra | 18-3599-2 | Catalog cross-reference for 3853850 |
Engine and Model Compatibility
Keep the engine brand, model, year, horsepower, rotation, and timing-cover configuration together when confirming fitment. Always compare the mounting pattern, hose connections, and the number on the original pump before ordering.
| Brand | Engine application | Years | Power or configuration | Reference numbers |
|---|---|---|---|---|
| OMC Cobra stern drive/outdrive | 4-cylinder GM marine engines | 1968–1998 | 100–140 HP | 3853850, 985429, 980477, 382218, 383953 |
| OMC Cobra stern drive/outdrive | 6-cylinder GM marine engines | 1968–1998 | 165 HP | 3853850, 985429, 980477, 382218, 383953 |
| OMC Cobra stern drive/outdrive | GM V6 marine engines | 1968–1998 | 150–165 HP | 3853850, 985429, 980477, 382218, 383953 |
| OMC Cobra stern drive/outdrive | GM small-block V8 marine engines | 1968–1998 | 170–350 HP | 3853850, 985429, 980477, 382218, 383953 |
| Volvo Penta stern drive/outdrive | GM V6 and small-block V8 marine engines | 1973 and later | Stamped or composite timing-chain cover configuration | 21124846, 3853850, 856364, 835390 |
Related catalog application guidance
Catalog information associates the 3853850 pump reference with GM V6 and small-block V8 marine engines, including 4.3L, 5.0L, and 5.7L configurations. Selected Volvo Penta applications include 4.3GXIE-M, GL, GXI, and related V6 model families. Selected MerCruiser applications use the corresponding small-block pump configuration and may differ by engine year, timing-cover design, and rotation. Verify the exact model and serial-number range before installation.
Technical Specifications
- Product type
- Bi-directional sea water circulation pump
- Installation
- Engine-mounted
- Intended system
- Raw-water or sea-water marine cooling system
- Engine family
- GM V6 and small-block V8 marine engines, plus the OMC 4-cylinder and 6-cylinder applications listed above
- Rotation
- Bi-directional; confirm the complete engine and pump configuration before installation
- Timing-cover compatibility
- Company Volvo Penta record specifies stamped or composite timing-chain covers
- Package type
- Single pump assembly
What’s in the Box
- 1 × Bi-directional sea water circulation pump assembly
A separate gasket set, hoses, clamps, mounting bolts, and other installation hardware are not listed as included in the company package record. Check the old gasket and mounting hardware and replace them as required for your engine.
Installation Notes
- Turn the engine off, allow it to cool completely, and disconnect the battery.
- Close the seacock or otherwise isolate the raw-water supply before removing hoses.
- Place a suitable container below the pump and disconnect the inlet and outlet hoses.
- Remove the mounting fasteners and take off the old pump.
- Clean the engine mounting surface and remove old gasket material without damaging the sealing surface.
- Confirm that the replacement pump, mounting pattern, hose connections, and rotation match the original application.
- Install the correct gasket or sealing material specified for the engine. The gasket is not listed as a separate included item for this product.
- Mount the pump and tighten the fasteners to the engine manufacturer’s specified torque.
- Reconnect the hoses and secure all clamps. Open the seacock and reconnect the battery.
- Start the engine, inspect all connections for leaks, and monitor engine temperature during the initial run.
Troubleshooting and FAQ
How do I confirm fitment?
Compare the complete engine brand, model, year, horsepower, rotation, timing-cover design, mounting pattern, hose connections, and the number on the original pump. The pump is intended for the OMC and Volvo Penta applications listed on this page; related MerCruiser applications must be confirmed against the specific engine configuration.
Is this pump bi-directional?
Yes. The company and catalog references identify this pump type as bi-directional. Confirm the complete pump and engine configuration before installation.
Does the product include a gasket?
This listing is for one pump assembly. A separate gasket set is not listed in the company package record. Use the gasket or sealing material specified for your engine application.
What are common signs of a failing sea water pump?
Symptoms may include overheating, reduced raw-water flow, water leakage near the pump, unusual bearing or seal noise, or visible corrosion. Stop operation and inspect the cooling system if any of these symptoms occur.
Will this fit every 4.3L, 5.0L, or 5.7L marine engine?
No. Displacement alone does not confirm fitment. Engine year, model family, timing-cover design, rotation, mounting arrangement, and serial-number range must also match.
What maintenance is recommended?
Inspect the pump periodically for leaks, corrosion, loose fasteners, damaged hoses, and abnormal noise. Follow the engine manufacturer’s service schedule for cooling-system inspection and replacement of wear items.
Safety and Important Information
- Verify the part number and physical configuration against the original pump and the engine service manual.
- Do not rely on engine displacement alone to determine compatibility.
- Close the seacock and disconnect the battery before removing the pump.
- Professional installation is recommended when the engine model, rotation, or cooling-system configuration is uncertain.
- This is an aftermarket replacement component, not an original branded OEM pump.
About Sea Sierra
- Marine replacement parts — Components selected for common sterndrive, inboard, and raw-water cooling applications.
- Application-focused fitment — Use the listed model, year, horsepower, rotation, and reference-number conditions when ordering.
- Practical replacement support — Confirm the original component and service-manual requirements before installation.
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